1. Field of the Invention
The present invention relates to a pneumatic tire which can improve uneven wear resistance while keeping running performance on icy roads.
2. Description of the Related Art
In order to improve running performance on icy roads, JF-2005-162058A1 proposes a pneumatic tire with a tread portion which comprises a plurality of blocks with cuts or narrow slits so called sipes. These sipes extend in an axial direction of the tire to divide the block into a plurality of block-pieces. Such blocks make friction force on icy roads greater due to each axially extending edge of the block-pieces. Accordingly, traction force and braking force of the tire on icy roads may be improved.
On the other hand, the rigidity of such blocks with sipes inevitably decreases. Especially, uneven wear such as heel and toe wear is liable to occur on circumferentially outmost block-pieces arranged in both sides of the block.